ouroboros-consensus-test-0.1.0.0: Tests of the consensus layer
Safe HaskellNone
LanguageHaskell2010

Test.ThreadNet.Ref.PBFT

Description

A reference simulator of the PBFT protocol under "ideal circumstances"

See step.

Synopsis

Documentation

data Outcome Source #

Outcome of a node leading a slot

Constructors

Absent

the leader hadn't yet joined

Nominal

the leader extended the networks' common chain with a valid block

(We're using nominal in the engineer's sense of "according to plan".)

Unable

the leader could not forge a valid block

Wasted

the leader forged a valid-but-irrelevant block, because it forged before sufficiently synchronizing

As of commit 4eb23cfe "Merge #1260", this only happens if a node leads in the slot it joins. In that slot, it forges before the mini protocols are able to pull in any of the existing nodes' chain, and so it re-forges the epoch 0 boundary block (EBB).

Instances

Instances details
Eq Outcome Source # 
Instance details

Defined in Test.ThreadNet.Ref.PBFT

Methods

(==)OutcomeOutcomeBool Source #

(/=)OutcomeOutcomeBool Source #

Show Outcome Source # 
Instance details

Defined in Test.ThreadNet.Ref.PBFT

Condense Outcome Source # 
Instance details

Defined in Test.ThreadNet.Ref.PBFT

Methods

condenseOutcomeString Source #

data Result Source #

The result of a reference simulation

There is only one way that multiple competing chains arise given the PBFT protocol under "ideal circumstances". When a node leads the slot in which it joins, it will forge before syncing. The fresh one-block chain it creates this way will be competitive if the other chains in the net are also only one block long. Once there is a two-block chain in the net, it will be the prefix of the net's one common chain going forward.

It is possible that the simulator is unable to statically determine which one-block chain will be the prefix of the common prefix going forward. In such a Nondeterministic scenario, the simulator inherently can not predict up to that slot. Moreover, it cannot predict past that slot, since the choice of chain affects who may be able to lead next. Therefore, the simulator offers no information beyond identifying this case.

Constructors

Forked !NumSlots !(Map CoreNodeId (Set SlotNo))

All the chains in the net consist of 1 block. The map contains the deterministic block selections made by nodes, identifying each one-block chain by the slot in which its block was forged.

Nondeterministic

The outcomes cannot be determined statically.

Outcomes ![Outcome]

The expected outcomes of each slot.

Instances

Instances details
Show Result Source # 
Instance details

Defined in Test.ThreadNet.Ref.PBFT

data State Source #

The state of a PBFT net with only one longest chain

Constructors

State 

Fields

Instances

Instances details
Eq State Source # 
Instance details

Defined in Test.ThreadNet.Ref.PBFT

Methods

(==)StateStateBool Source #

(/=)StateStateBool Source #

Show State Source # 
Instance details

Defined in Test.ThreadNet.Ref.PBFT

advanceUpToPBftParamsNodeJoinPlanStateSlotNoState Source #

Iterate step

POST nextSlot is >= the given slot

definitelyEnoughBlocksPBftParamsResultBool Source #

Confirm that the simulated chain includes at least k blocks within every 2k-slot window

nullStateStateBool Source #

There are no recorded forgings

pbftLimitIntegral a ⇒ PBftParams → a Source #

How many blocks in the latest k-blocks that a single core node is allowed to have signed

simulateHasCallStackPBftParamsNodeJoinPlanNumSlotsResult Source #

Run simulateStep, switching to iterating step once there is a 2-block chain

See Result.

simulateShortHasCallStackPBftParamsNodeJoinPlanNumSlotsEither DetOrNondet ShortState Source #

stepPBftParamsNodeJoinPlanState → (Outcome, State) Source #

Advance the state by one slot

ASSUMPTION Any new valid block is immediately selected by all nodes.

This assumption seems mild because of PBFT's fixed round-robin schedule; it primarily constrains the network topology, network outages, node restarts, clock skew, etc to be trivial. In other words, "ideal circumstances".

The assumption is useful in this reference implementation because it lets us maintain a single "global" State common to all nodes.

viablePBftParamsSlotNoNodeJoinPlanStateBool Source #

True if there will be no necessary violations of "k-blocks in 2k-slots" before the given slot, assuming all remaining nodes join ASAP

PRE the given parameters and state are not already tooSparse params st

NOTE this function does not consider the competition between 1-block multichains, so definitelyEnoughBlocks must still be checked to confirm